Electrode and process of making the same.



' UNITED STATES PATENT OFFICE.

'J'ORGEN ERNST THOMSEN, OF JERSEY CITY, NEW JERSEY, ASSIGNOB TO THE JOSEPH DIXON CBUCIBLE COMPANY, .OF JERSEY CITY, NEW JERSEY, A CORPORATION OI! NEW JERSEY.

ELECTRODE AND PROCESS OF MAKING- THE SAME.

No Drawing.

tain new anduseful Improvements in Electrodes and Processes of Making the Same,

of which the following is a specification.

My invention relates to electrodes or electrical conductors and particularly to that class of electrodes which are composed partly of carbon. An object of my inven-' tion is to produce a harder and stronger article of this classthan those in common use at present. Electrodes of my invention are of particular value as dynamo brushes, but they have numerous other uses.

In order that my invention may clearly be understood, I will describe in detail a specific embodiment of it.

In producing my electrode, I first mix together finely divided carbon, a phenol or creos'olv or a compound or mixture containing phenols and creosols, such as pitch, tar or creosote oil, and formaldehyde or a formaldehyde derivative, such as paraformaldehyde, and hexamethylenetetramin;

I find it preferable not to have the carbon content of this mixture reduced-t0 a uniform degree of-fineness. It should preferably consist of particles of graphite of diflerent sizes. If formaldehyde is used, I find it desirable also to add a small quantity of alkali, as, for example, ammonia, to 35V the mixture;

The strength of the final material as well asits electrical conductivity may be varied by varying the proportion of the carbon to the other ingredients in the mixture. One formula whichI have found to give a very satisfactory product is as follows 64% carbon (containing particles of different sizes),

18% coal tar, 15% creosote, 3% hexamethylenetetramin. The above described mixture is then heat ed to a temperature not exceeding 450 F.

to drive ofl the volatile matter and the remaining mass is ground to a powder.

The powder thusfornied is then pressed into molds at. a pressure :which must vary according to thehardness and density dein the product. When making the Specification of Letters Patent.

Patented Oct. 16, 1917.

Application filed. February 2, 1917. Serial No. 146,204.

maldehyde and the phenols and creosols.

It is necessary to surround or cover the blocks w1th fine carbon during the calcining or otherwise prevent oxygen from comingin contact with the blocks when heated about a red heat. In calcining, thetemperature must be raised very slowly up to the point where the condensation products of the formaldehyde and the cresols and phenols are fully carbonized and all the gases from their decomposition have been expelled. When this point is reached, the calcination is complete and a further increase in the temperature has no effect.

I wish it clearly understood that my invention is by no means limited to the specific embodiment which I have described. My invention is defined in the following claims, in which I haveused the word tar in a generic sense to include either wood tar, coal tar or a mixture of the two or any substance or substances containing phenols or creosols or both. 1 J

1. An electrode consistin of a hard noninfiammable body produce from a mixture of carbon, tar, and a compound containing the formaldehyde radical.

2. An electrode consisting of a hard non inflammable body produced from a mixture of finely divided carbon including particles 5. A process of making electrodes, com- .prising mixing together cfilion tar and a compound containing the fdrmal dehyde radical, pressing the mixture into blocks, and calcining the blocks at a temperature above the decomposition point of the condensation products present.

6. A process of making electrodes, comprising mixing together finely divided carbon containing particles of different sizes, tar, and a compound containing the formaldehyde radical, pressing the mixture into blocks, and calcining the blocks at a temperature above the decomposition point of the condensation products present.

7. A process of making electrodes, comprising mixing carbon, tar, and a compound containing the formaldehyde radical, heating the mixture sufiieiently'to drive ofl the volatile matter, pressing the mixture into blocks, and calcining the blocks at a temperature above the decomposition point of thecondensation products present.

8. A process of making electrodes, comprising mixing together carbon, tar, and a compound containing the formaldehyde point of the condensation products present.

9. A process of makin electrodes, comprising mixing together nely divided carbon about 6L%, tar about 33%, and formaldehyde derivative about 3%, heating the mixture to a temperature not exceeding 450 F. to drive Oil the volatile matter, grinding f the-resulting mass to a powder, pressing the powder into blocks, and calcining the blocks at a temperature above the decomposition point ofthe condensation products present.

JORGEN ERNs'r THOMSEN. 

